Holddown clamp



Sept. 1, 1953 ZWICK 2,650,523

HOLDDOWN CLAMP Filed April 14, 1952 34 f0 [2 J4 J8 n 6 H 2,, i

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KURT M/f/ Patented Sept. 1, 1953 .HOLDDOWN onAMr Kurt Zwlck, Munich,Germany, assignor to Hans Deckel, Munich-Solln, and Friedrich WilhelmDeckel, Post Tutzing, Germany T Application April 14, 1952, Serial No.282,242

7 InGermany April 27, 1951 The present invention relates to a device forfastening work pieces or the like to holding elements, for example,machine tables, which comprises a double-armed clamp member, which is sotightened by means of a screw device engaging with the holding elementso that it rests with one arm on an equalizer arrangement supported onthe holding element, and presses the work piece with the other armagainst the holding element.

Heretofore in the art, devices of this type have employed a screwarrangement consisting of a screwbolt which could either be screwed intotheclamp table and pressed with its head onto the clamp member, or whichcould have its. head engaged in a groove of the clamp table, the clampmember being tightened by means of a-nut engaging the bolt. In order toobtain a wide size-range of work pieces in these arrangements the screwbolt was necessarily quite long. This is disadvantageous insofar as thefastening of low work pieces is concerned as a considerable portion ofthe screw bolt either projects out on the lower side of the clamp table,or extends abovethe device and thereby has a detrimental effect on thefreedom of movement of the clamp table or the work piece holder. Toavoidthis disadvantage the screw bolts have to be adapted ineach case asexactly as possible to the dimensions of the work pieces, which wouldrequire a large number of screw bolts of various lengths and theirfrequent exchange which is, therefore, unfavorable because of thedemands upon material and working time.

I It is the object of the present invention to avoid these disadvantagesand provide a fastening device, which with the least external dimensions possesses a particularly wide tension range is operable easily andquickly and whose individual parts always form a unitary assembly.

According to the present invention this is achieved by 'a screwarrangement consisting of a threaded socket and a screw member that canbe screwed into the socket, where the screw member is provided withthreads over almost its entire length and the bore of the socket is madeat least approximately as long as the threaded part of the screw member.

A particularly advantageous construction of the fastening device isachieved according to other features of the invention by arranging aclamp member on a lower part of the device which is rotatably mountedabout the longitudinal axis of the screw device and which co- Operateswith an equalizer member formed with 5 Claims. (01. 90-59)accurately'arranged steps, the equalizer me her being likewise mountedswingably about the longitudinal axis of the screw device.

The use of a stepped base for a fastening device has been knownheretofore. However, in the prior devices the stepped base of fasteningdevice was not arranged swingably about the axis of the screw device,but was loosely rotatable at one end of the clamping member so that theswivel pivot, of the base of fastening device, projected beyond theclamping member.

Such an arrangement, however, also has the aforementioned disadvantagethat in order to achieve a wide clamping range the axis of rotation hasto be made correspondingly long, and. thus interferes with the freedomof movement.

of the tool carrier. i

The invention will be more clearly understood from the specificationhereinafter following by reference to the accompanying drawings inwhich:

Figure l is an elevational view of the device: with certain of the partsbroken away and shown. in section; Fig. 2 is a plan view; Fig. 3 is anele-- vational view showing the application of the- I4 is at leastapproximately as long as the thread part of the bolt l2. An equalizerdevice is rotatably arranged about the longitudinal axis of the bolt 12and sleeve 14. This consists of a lower part 22 arranged between theupper end of the sleeve l4 and the clamp member ID, in such away that.apertured part 23 surrounds the upper end of the sleeve l4. The lowerpart 22 has a downwardly projecting arm 24 which cooperates with astepped equalizing member 26 which can be swivelled about the sleeve H.A spring 28 tends to hold the lower part 22 together with the clampmember l0 against the head of the bolt l2.

The clamp member In is provided with a longitudinal slot 30 for thepassage of the bolt l2, which makes it possible to adjust the clampmember ID relative to the lower part 22 transversely with respect to thelongitudinal axis of r 3 the bolt l2 and sleeve M. This freedom ofmovement for adjustment is limited by two upwardly extending lugs 32 onthe lower part 22 which cooperate with corresponding abutments 34 of theclamp member IE].

In fastening a work piece 36 lying on the machine table 18,; theequalizer agrangement; com! prisin part-s22, 214 and. 6 is o. eadiusteditg level corresponding to the height of the work piece and thescrew device has to be operated by;

tightening the bolt I2, until the work piece 36 is tightly clamped bythe free arm of the clamp member In.

Fig. 1 shows the fastening- -o r secu zing; device in a position whichcorresponds to the smallest; work piece level that can be clamped. In,1*?ig 3, on the other hand, the device is representedin; securing awork piece 36a which is almost twice the height of the Work piece 36 inFig. The. clamping range of the fastening device can, howr rsl e enlargst ;v ur e a rdi g: l ss la h n of; am-p member; H1- is f e as shown at38419 engage andE fasten the; workpiece 35b. this-case theconstructional; height of is, only slightly larger than the height .h eet e ie y it' should also; be mentionedthat the individual, parts f thedevice form; a unitary es mhlvasa esult 0i heir adv n e us maixri-iaudlarams meht,throu which a d a Qn r t h, s render dlpo s cert in: pr fe redm od s. f. the rh' htieh have b en shown t. e lize a uI-th r mod fi ios-and: n es. m y be made and; t: es r d; hat it; understood that no.imitations upon. th .v inv ntion are intend other than may be imposedbythe scope of the annehd d; aims la m; as.- new and; desireto; secureby Le ers-Remi of: he United. States is. as; follows:

1. A clamping device as set forth in claim 5, in;which;a clamp; isrotatable around the longituglihill. of; the: screw, device and;cooperates with Sffljidi equalizer member which is. also rotatablearound: the longitudinal axis of the screw,- device,., andrwherein, aspring is disposed around. the longitudinal axis of: thescrew devicewhich presses: the. clamp against the head of the bolt.

2. A clamping device as set forth in claim 5;

whichzincludes. a clamp memberhavingat'l'east two abutment surfaces. anda lower part coacting: with; said clamp: member, said lower part having:corresponding countersurfaces which limit the trahsverseadjustmentofthe-clamp member, and wherein said; lower part has an aperturedportion-- into:. wh-ichr the threaded': sleeve partly pene-- trates;

3: A- clamping device as set forth inclaim 5 in. lt'hich; the threadedvsleeve is provided at its lower'end, with av head by meansof which itcanbelinserted in,correspondinglyshaped grooves of-= hold ng part.

rgdtzclamnihgdevice for securing work pieces sleeve, a clamp memberengaged by said headed bolt, a lower part engaged by said bolt beneathsaid clamp member, said lower part having a projection, dependingtherefrom and adjustably engaging; said stepped equalizing member, saidlamp; mfilnben-hatving one end thereof in enheaded olt wh n: adiu t lygaged: inv he;

screw-threaded bore of said sleeve operates itsecure said; elementstogether in a unitary. as;-

A; clamping device forysecuring workpieces; h li e h n em nts; such;as,machine:r tables wh ch p se a; doubl rarmedg clam a holding element,an equalizer arrangementsupeported; n the o d n lementi 8259mm devicengaging saidclamp and said: holding element; o: hat aid amhi rests;with ne: arm. on said; equalizer r n em t andthe: other arm. su

ported on the; workpiece;- said, screw arrangerv ment CODSiStiIIg Qf a.threa1ded,socketand; ascrew mem erw iu tablw en a n s id socket; said:-screw memberbeing; provided with, threads oven: substantially its;entire length and th8-b0re 0fi the socket being; at;leastqapproximately: as-;1'0ng: as hehreaded partioi thGtSCIiGWE member,said. clamp-member being adjustable transverselywithrespect.todillfidongilludinal axis of the screw mem her: and: a;sleevemotatably: mounted. about the longitudinal; axis of. theiscrewmember and connected; with, said holding. element and a down wardlyprojecting, arm; on: said clamp. engageable with said; equalizing.member, said: equalizing membenbeingiswivelly: mounted about saidsleeve'.

Z=WIGK.

References; Qited; the file; of: this; patent: UNITED STATES PATENTS INumber Name. Date 13685399 Andrew, y Oct, 2; 1928;. 1 801 222 Cavev gApr. 14,1931,

FQREIGN: PATENTS:

Number Country Date 236-3421 Germany Dec. 9, 19,09 s nzee France- Jan.30,119,2 1 898,683 France July 1 0, 1944j

